Long-term Efficacy and Safety of High-frequency Spinal Stimulation for Chronic Pain

Objective: The aim of our meta-analysis was to systematically assess the enduring effectiveness and safety of high-frequency spinal stimulation (HF-SCS) in the management of chronic pain. Methods: We developed a comprehensive literature search strategy to identify clinical trials investigating the efficacy of high-frequency spinal stimulation for chronic pain. The search was conducted in multiple databases, including Web of Science, Cochrane, PubMed, and Embase, covering the period from 2004 to 2023. The inclusion and exclusion criteria established for this study were applied to screen the eligible literature by carefully reviewing abstracts and, when necessary, examining the full text of selected articles. To assess the quality of the included studies, we utilized the Risk of Bias assessment tool provided by the Cochrane Collaboration. The PRISMA method was followed for the selection of articles, and the quality of the articles was evaluated using the risk assessment table for bias provided by the Cochrane Collaboration. Meta-analysis of the selected studies was performed using Review Manager 5.4 and STATA 16.0. Effect sizes for continuous data were reported as mean differences (MD) or standardized mean differences (SMD), while categorical data were analyzed using relative risks (RR). Results: According to our predefined literature screening criteria, a total of seven English-language randomized controlled trials (RCTs) were included in the meta-analysis. The findings from the meta-analysis demonstrated that HF-SCS exhibited superior efficacy in the long-term treatment of chronic pain when compared with the control group (RR=2.44, 95% CI: 1.20-4.96, P =0.01). Furthermore, HF-SCS demonstrated a statistically significant improvement in the Oswestry Disability Index score (mean difference MD=3.77, 95% CI: 1.17-6.38, P =0.005). However, for pain assessment (standardized mean difference SMD=−0.59, 95% CI: −1.28 to 0.10, P =0.09), Patient Global Impression of Improvement (PGI-I) score (MD=0.11, 95% CI: −0.66 to 0.88, P =0.78 for 6 months; MD=0.02, 95% CI: −0.42 to 0.43, P =0.97 for 12 mo), Clinical Global Impression of Improvement (CGI-I) score (MD=−0.58, 95% CI: −1.62 to 0.43, P =0.27 for 6 mo; MD=−0.23, 95% CI: −0.94 to 0.48, P =0.52 for 12 mo), and occurrence of adverse effects (odds ratio [OR]=0.77, 95% CI: 0.23-2.59, P =0.67), HF-SCS did not show statistically sufficient effects compared with the control group. Conclusions: The findings from our comprehensive review and meta-analysis offer encouraging data about the prolonged efficacy and safety of HF-SCS in chronic pain management on some but not all outcomes. Recognizing the constraints of the existing evidence is crucial. Additional clinical trials, meticulously planned and stringent, are essential to bolster the current body of evidence and reach more conclusive findings.